Revised 3 Septembr 2021

Humankind’s survival requires consumption of food, water, clothing, warmth, and shelter. Each of these basic needs are provided by the environment. Material consumption includes consumption of minerals, fossil fuels, and ecological systems which provide both food and resources. Continued growth in material consumption of ecological systems is impossible on a finite planet because continued growth will ultimately and inevitably surpass the carrying capacity of any ecological system. There are strong signals that excessive material consumption by humankind has already exceeded Earth’s carrying capacity (Cohen, 1995). The future sustainability of human civilisation is becoming increasingly more jeopardised with each passing decade

Consumption, production, and energy, are inextricably connected. Without production there can be no consumption, and without energy there can be no production. In early years of civilisation, production of the above essentials was enabled by stint of human effort and use of basic tools. We now use energy slaves in the form of machinery to replace human labour and we now rely on sophisticated technology in place of simple tools (Cottrell, 1955). Human created money and debt enable transactions and purchase of energy (Graeber, 2011), but it is energy itself that enables and drives production (Smil, 2017). Energy is subject to the Laws of Thermodynamics, and it is these laws and not laws or theories of economics which dictate the limits of production and possible pathways to sustainable human settlements.   

Humankind will not prove to be an exception to the laws of growth and thermodynamics. Humankind is and will continue to be subject to the same laws of growth as any other organism on Earth. When our high-grade fossil fuel energy resources are eventually too expensive in energy terms to further extract from the ground, humankind will either live in a homoeostatic, steady state, symbiotic relationship with the entire ecosystem on Earth or face extinction. This web publication assumes that humankind will continue to survive for many more millennia into the future. 

The following diagram maps growth in our human population and use of resources, including energy, from the past to the present and projects alternative pathways into the future. 

Pathway A shows continuing growth into the distant future. This pathway is an impossibility. Non-renewable energy sources such as oil, coal, gas, and shale are finite and the surface area of our planet Earth is also finite. Our human population simply cannot continue to grow forever, and because humankind is totally dependent on using energy for survival, our species will either eventually become dependent on using renewable energy resources or face extinction. 

Growth in human population, energy use, and the use of mineral resources cannot continue. At some stage in the future there will be a transition from growth to either a steady state or a decline and eventual collapse to extinction. Possible future paths include Pathway B which transitions smoothly from growth to steady state without any decline, Pathway C which declines from growth to a lower level of steady state, and Pathway D which collapses from growth to extinction. 

The actual level of steady state that is possible as depicted by Pathway C depends on the availability of renewable energy and mineral resources, the level of human population, and the carrying capacity of our species within the total ecosystem on Earth. There would be fluctuations in the level of steady state because regardless of whether future society is based on a market or planned economy or a mixture of both, there are likely to be periodic runs on the use of resources which need to be curbed and reeled back in. 

Whatever the overall level of steady state might be, there will be a gradual and inevitable decline in that level because it is physically impossible to 100% recycle the mineral resources that we are currently reliant on using in a technological society. As time progresses, it will become increasingly energy expensive to extract mineral resources from the ground. The peak production process that applies to extracting oil and other non-renewable energy sources from the ground also applies to mineral resources used in a technological society. 100% recycling is possible in natural ecosystems, so an inevitable decline of a technological society might ultimately result in a return to a hunter-gatherer society with a much-reduced population in the far distant future. As Nicholas Georgescu-Roegen (1971, p. 304) has put it, every additional Cadillac today represents a reduction in the life support system of distant future generations. Ultimately Earth will face a fiery death when in a few billion years’ time the Sun will expand into a Red Giant. We need not dwell on the far distant future. Our immediate challenge is to confront a transition from fossil fuels to renewable energy in the here and now.  

Pathway C, a decline over a hump down to a lower level of steady state, is more likely than a gentle transition from growth to steady state as shown in Pathway B for the following reasons. Humankind currently faces a double whammy. To avoid severe consequences of climate change, we need to curb our use of fossil fuels which adds greenhouse gases to the atmosphere. We are still reliant on using energy, so we need to transition over to renewable energy sources. Setting up alternative infrastructure that provides and supports renewable energy will require additional use of fossil fuels at the very same time that we need to curb our use of those fossil fuels. In the long run, viable renewable energy source systems need to be able to maintain and replace themselves in order to be truly sustainable, but renewable energy systems are initially unable to bootstrap themselves through a transition without assistance of fossil fuels in the short-term. 

There are already indications that we have reached the stage of peak conventional oil where the rate of conventional oil production has started to decline. Ideally, humankind needs to divert the use of fossil fuels from unnecessary consumption to that of investment in renewable energy. However, regardless of voluntary curbing of the use of fossil fuel on consumption, peaking of all forms of fossil fuels will increasingly limit the rate of supply of fossil fuels in the future. Delays in enabling a transition from fossil fuels to renewable energy can only but exacerbate the difficulties of transition over time. 

A critical question is whether we can simultaneously curb our generation of greenhouse gases and transition to non-renewable energy. Given our response over the last 40 years to early warnings of climate change and the consequences of peak oil, there are good reasons for limited confidence that both targets will be met. Given the multiplicity of information and data from diverse and reliable sources of information, there is a high possibility that the future before 2100 will be strife for millions around the globe. Society has ignored warning signals about both climate change and peak oil over the past 40 years and tends to respond only to emergencies. It is likely that insufficient action will be taken to fully address the issues of climate change, peak oil, and the need for zero population growth. 

The elephant in the room is population growth. The need to curb population growth has been ignored and shelved. Steady state for humankind requires zero population growth (ZPG). If all countries were to immediately adopt a policy of ZPG, then the global population would continue to grow for a number of decades despite the low growth and even declines in the natural population of several developed countries. Continued increases in population during a transition from fossil fuels to renewable energy can only but result in a Sisyphus like undermining of any efforts for a smooth transition. 

Continuing with a focus on Pathway C, renewable energy currently includes hydro-electricity, phytomass (plant material), wind power, solar energy concentrators, photovoltaic cells, geothermal power, and tidal waves. The scale and extent that each of these energy systems can be used by future human settlements depends on the availability of mineral resources needed to create these energy systems, the resulting net energy produced by these energy systems, and the convenience of the form of energy that is generated. For example, hydrogen is a convenient concentrated form of energy suitable for transport, but the production of hydrogen does not result in net energy because it takes more energy to produce than the energy content available in the hydrogen. Hydrogen is a convenient carrier of energy, but is not an additional energy source independent of the energy required to produce it. 

Nuclear fission as an energy source involves ethical issues. We bear a responsibility to future generations of humankind and other species not to endanger their existence and leave them a heritage of nuclear waste that will have to be guarded for centuries. Some energy researchers advise against ruling out nuclear energy. These issues are fully addressed in Section: Nuclear Energy. New Zealand is fortunate in that the use of nuclear energy is unnecessary because New Zealand already has a high level per capita of hydro-electricity, high potential for wind power, and potential to expand its current generation of geothermal electricity. 

This web publication is concerned with technology that we have already developed. Should our current level of technology improve in the future to include nuclear fusion, then the carrying capacity and the consumer level of life could both increase, but within limits.  

Humankind continually comes across limits in every sphere of life. The ultimate peaking and decline of easily accessible high-grade energy fossil fuels and mining of minerals are but some of many limits. A crisis can develop when humankind does not accept there are limits. Humankind induced climate change is an example. Limits exist and we need to accept them and act accordingly for humankind to continue to survive in future millennia. A growth philosophy has enabled development of civilisation in the past. Further development does not require further growth. We now need to cast aside a growth philosophy which ignores the consequences of limits.  

We, our children, and our grandchildren are privileged to be living in a period of transition that is unparalleled in the entire history of humankind. The decisions and actions that we have made in the past and the decisions and actions that we will make over the next number of decades have and will limit the options of current and future generations. We need clear visions of pathways in a transition from growth to steady state. Hopefully this web publication provides some measure of contribution to that vision.